ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-6-3407-2006Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic siteVirkkulaA.1TeiniläK.1HillamoR.1KerminenV.-M.1SaarikoskiS.1AurelaM.1ViidanojaJ.2PaateroJ.1KoponenI. K.3KulmalaM.41Finnish Meteorological Institute, Erik Palménin aukio, 00560, Helsinki, Finland2Department Department of Chemistry, Laboratory of Analytical Chemistry,University of Helsinki, 00014 Helsinki, Finland3University of Copenhagen, Department of Chemistry, Universitetsparken 5, 2100 Copenhagen, Denmark4Department of Atmospheric Sciences, Aerosol and Environmental Physics Laboratory, University of Helsinki, 00014 Helsinki, Finland2108200661134073421This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article is available from http://www.atmos-chem-phys.net/6/3407/2006/acp-6-3407-2006.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/6/3407/2006/acp-6-3407-2006.pdf

Aerosol chemical composition was measured over the Atlantic Ocean in
November&ndash;December 1999 and at the Finnish Antarctic research station Aboa in
January 2000. The concentrations of all anthropogenic aerosol compounds
decreased clearly from north to south. An anthropogenic influence was still
evident in the middle of the tropical South Atlantic, background values were
reached south of Cape Town. Chemical mass apportionment was calculated for
high volume filter samples (D<sub><i>p</i></sub>&lt;3 μm). North of the equator
70&ndash;80% of the aerosol consisted of non-sea-salt species. The
contribution of sea salt was ~25% in the polluted latitudes,
&gt;80% in the Southern Ocean, and &lt;10% at Aboa. The contribution of
organic carbon was &gt;10% in most samples, also at Aboa. The correlation
of biomass-burning-related aerosol components with <sup>210</sup>Pb was very high
compared with that between nss calcium and <sup>210</sup>Pb which suggests that
<sup>210</sup>Pb is a better tracer for biomass burning than for Saharan dust. The
ratio of the two clear tracers for biomass burning, nss potassium and
oxalate, was different in European and in African samples, suggesting that
this ratio could be used as an indicator of biomass burning type. The
concentrations of continent-related particles decreased exponentially with
the distance from Africa. The shortest half-value distance, ~100 km,
was for nss calcium. The half-value distance of particles that are mainly in
the submicron particles was ~700&plusmn;200 km. The MSA to nss sulfate
ratio, R, increased faster than MSA concentration with decreasing
anthropogenic influence, indicating that the R increase could largely be
explained by the decrease of anthropogenic sulfate.